菊酯类药剂对草地贪夜蛾的毒力及对钠离子通道的诱导特性

为明确菊酯类药剂对草地贪夜蛾Spodoptera frugiperda的防治效果,采用点滴法在室内测定高效氯氟氰菊酯、高效氯氰菊酯、联苯菊酯、溴氰菊酯和茚虫威原药对草地贪夜蛾3龄幼虫的毒力,利用实时荧光定量PCR技术测定3龄幼虫在这5种药剂诱导不同时间下其体内钠离子通道基因片段的表达量变化。结果显示,高效氯氟氰菊酯、溴氰菊酯、联苯菊酯、茚虫威和高效氯氰菊酯这5种药剂处理草地贪夜蛾3龄幼虫24 h后的LD50值分别为74.911、83.280、152.662、179.372、567.250 mg/L;处理48 h后的LD50值分别为18.946、67.874、120.888、132.790、461.635 mg/L;同时发现草地贪夜蛾3龄幼虫钠离子通道基因的表达均呈现不被诱导或诱导下调现象,表明草地贪夜蛾幼虫可通过降低靶标基因的表达量进而减少药剂对其的毒性。表明供试4种拟除虫菊酯类药剂和1种氯虫苯甲酰胺类药剂可作为草地贪夜蛾田间应急防控药剂施用。

Toxicity of pyrethroid pesticides to fall armyworm Spodoptera frugiperda and its inducing properties of sodium ion channels

In order to clear the control effect of pyrethroid pesticides to fall armyworm Spodoptera frugiperda, the toxicity of lambda-cyhalothrin, beta cypermethrin, bifenthrin, deltamethrin and indoxacarb against the third instar larvae of S. frugiperda by drop method and the expression level of sodium channel gene in the third instar larvae under the induction of these five insecticides was detected by quantitative real-time PCR. The results showed that the LD₅₀ values of lambda-cyhalothrin, deltamethrin, bifenthrin, indoxacarb and beta cypermethrin after 24 h treatment of the third instar larvae of S. frugiperda were 74.911, 83.280, 152.662, 179.372 and 567.250 mg/L, respectively. After 48 h of treatment, the LD₅₀ values were in the order of 18.946, 67.874, 120.888, 132.790 and 461.635 mg/L, respectively. Meanwhile, the expression level of sodium channel gene was showed no change or down-regulated. It indicated that the fall armyworm larvae could reduce the toxicity of the insecticides by reducing the expression of the target gene. This study was preliminary cleared that the indoor insecticidal activity of four pyrethroid insecticides and one chlorobiobenzoamide insecticides and revealed these insecticides can be used as field emergency prevention and control of S. frugiperda at present.